Are there any advantages to this besides being the convention? Always wondered that.
- 'knots' is faster to say on the radio than 'kilometers per hour'
- the way the world is divided in wgs84, maked it so that 1 degree of latitude equals exactly 60 miles. So that makes quick measurements a bit easier.
What with the Earth being an ellipsoid and not a sphere and all that?
For a sailor in the 16th century, assuming a sphere was perfectly adequate when combined with 1 degree = 60 nautical miles.
The geoid model is the surface of gravitational equipotential and is a "shape of the gravitational field" not a "shape of the physical earth".
If we were discussing 16th century sailors rather than 21st century aviation you might have had a point.
The origin of nautical miles is from 16th century sailors.
And 21st century aviation doesn't need anything more accurate than WGS84. The people who need custom geoid models and local coordinate systems are surveyors.
I believe you're thinking of distance between lines of longitude which converge at the poles and are at maximal seperation at the equator.
I was referring to the arc distance (surface distance) between lines of latitude which don't converge to zero but do get a little smaller closer to the poles (due to the lesser minor radius of the ellipsoid shape to the earth - oblate sphereoid, squashed sphere, not a perfect ball, etc.)
But it really helps you as in you are able to pick any distance you want to fly on the map and by moving your fingers to the Y axis roughly guess the distance within a few seconds. Even in a very small cockpit and with turbulence. So i absolutely see the need for this with relation to navigation.